Methods and compositions for killing weeds



Patented Mar. 12, 1946 2,396,513 METHODS AND COIVIPOSITIONS FOB KILLING WEEDS Franklin D. Jones, Upper Darby, Pa., assignor to American Chemical Paint Company, Ambler, Pa., a corporation of Delaware No Drawing. Application June 12, 1945, Serial No. 599,117

22 Claims.

The present invention relates to methods and compositions for killing growing weeds.

The term "weed is used in the present disclosure in its broadest sense, namely, a plant which persists in growing where it is not wanted. This use of the term is broad enough to include not only plants harmful to man or animal, such as those of the Rhus family (poison ivy and poison oak), bindweed, and plants such as wild garlic and French weed, which have a bad effect on dairy products, but also otherwise desirable plants such as Japanese honeysuckle or lawn grasses growing on driveways.

Weeds, as a general rule, are able to grow under adverse conditions and their control presents a very difficult and troublesome problem to farmers.'

Prior to the research which resulted in the present invention, the most effective methods involved the use of chemicals such as common salt, chlo-' rates, iron sulphate, ammonium sulphate, carbon disulphide, ammonium sulfamate, sodium dinitroortho-cresylate, sodium arsenite, and oil. All of these materials are low in unit cost, but high in cost per acre when applied in suficient quantitles to kill the weeds and they may sterilize the soil for long periods. Moreover, many of them are hazardous, being poisonous or explosive, or both. Most of them are corrosive to the equipment and dimcult to handle. Moreover, they tend to kill the top of the plant without killing the roots permanently.

The primary object of the invention is to improve chemical methods for eradicating weeds in an active state of growth.

Another object of importance is to provide a wholly new class of systemic or translocated herbicides.

Another important object is to provide compositions for the purpose of eradicating growing weeds which are considerably less expensive, more economical, safer to use, and more effective than previously used chemicals.

The invention is based in part upon the observation or discovery that certain compounds, which will hereinafter be referred to as "compounds of the invention at certain concentrations, are systemic poisons for higher plant life, and may be used as the active. ingredients of herbicides.

The compounds, of the invention are the phenoxy, phenylmercapto, phenylimino, naphthoxy, napthylmercapto, and naphthylimino monocarboxylic aliphatic acids, their esters and salts. The ring portion of the compounds may contain one or more substituents such as halogen,

OH, NHz, HSOa, N02, or an alkyl or alkylene group such as for instance methyl, ethyl, propyl, butyl, methoxy and ethoxy.

The term "aliphatic acids is broad enough to include both the saturated and unsaturated acids. For practical reasons, acids having two to nine carbon atoms ar preferred, but the invention is not restricted thereto. As examples of suitable acids may be mentioned formic, acetic, propionic, butyric, valeric, hexoic, acrylic, methyl acrylic, etc.

The term esters" is broad enough to cover the esters corresponding to both the saturated and unsaturated alcohols. As examples of suitable esters may be mentioned the alkyl and alkylene esters such as methyl, ethyl, propyl, butyl, amyl, octyl, lauryl, oleyl, allyl, and isoprene esters, the esters of polyhydroxy alcohols such as the esters of ethylene glycol and of the polyethylene glycols, and the aralkyl esters such as the benzyl esters.

The polyethylene glycol ester of a desired acid.

may be made by heating a polyethylene glycol, such as Carbowax of molecular weight of 600 or over, with the acid in the presence of a catalyst such as sulphuric acid. The Carbowaxes are products of Carbide & Carbon Chemicals Corp., New York, N. Y.

The term salts is broad enough t include the alkali and alkaline earth salts such as sodium, potassium, lithium, ammonium, magnesium, calcium, the acid salts such as the sodium and potassium acid salts, the salts of other metals such as copper and iron, and the substituted organic ammonium salts such as the salts of methylamine, trimethylamine, diethylamine, monoethanolamine, triethanolamine and isopropanolamine.

The following is a representative list of compounds, which have been found to be suitable for the purposes of this invention:

Phenoxyacetic acid, its alkyl substitution products such as 4-methyl phenoxyacetic acid, 2.4- dimethyl phenoxyacetic acid, 3.4-dimethyl phenoxyacetic acid, 3.5-dimethyl phenoxyacetic acid, and 2.4.5-trimethyl phenoxyacetic acid, its alkoxy derivatives such as i-methoxy phenoxyacetic acid, its halogen substitution products such as 2-chloro-phenoxyacetic acid, 4-chloro-phenoxyacetic acid, 2.4-dichloro phenoxyacetic acid, 2.4.5- trichloro-phenoxyacetic acid, 2.4.6-trichloro-phenoxyacetic acid, 2.3.4.6-tetrach1oro-phenoxyacetic acid, pentachloro-phenoxyacetic acid, 4-bromophenoxyacetic acid, 2.4-dibromo-phenoxyacetic acid, 2.4.6-tribromo-phenoxyacetic acid, 4-iodophenoxyacetic acid, 4-fluoro-phenoxyacetic acid and 2.4-difiuoro-phenoxyacetic acid, its nitrosubstitution products such as 4 -nitro-phenoxyacetic acid, and the esters and salts.

Phenylimino-acetic acid (phenyl glycine) and phenylmercapto-acetic acid, their halogenated products such as 2.4-dichloro-phenylimino-acetic acid, 4-chloro-phenylmercapto-acetic acid, and

2.4-dichloro-phenylmercapto-acetic acid, and the esters and salts.

l-naphthoxyacetic acid, 2 riaphthoxyacetic acid, l-naphthoxy-alpha-propionic acid, 2-naphthoxy-alpha-propionic acid, their halogen substitution products such as 2-chloro-1-naphthoxyacetic acid and 2.4-dichloro-l-naphthoxyacetic acid, and the esters and salts.

The naphthyl glycines, e. g. l-naphthyliminm acetic acid and 2-naphthylimino-acetic acid, their halogen substitution products such as 4- chloro-l-naphthylimino-acetic acid, and the esters and salts.

1-naphthylmercapto-acetic acid and 2-naphthylmercapto-acetic acid. their halogen substitution products, and the esters and salts.

The foregoing list is given by way of illustration only, and the corresponding derivatives of the corresponding unsaturated acids, e. g. acrylic acid and its homologues, may be used.

Some, but not all of the foregoing compounds are plant hormones; i. e. they serve to promote plant growth, when used in very minute concentrations in the form or solutions or dusts, or in considerably higher concentrations in the form of pastes in such materials as fats or greases (e. g. lanolin). For the purposes of the present invention, the aforementioned compounds, whether or not they are plant hormones, must be used in muchhigher concentrations than have ever been used for plant growth promotion. The minimum effective concentration depends upon a number of factors such as, for instance, the particular species of plant to be eradicated, the particular type of vehicle or medium, and whethe or not an adjuvant is used. There is no upper limit to the concentration, except that dictated by economy.

It the active herbicidal ingredient is used in an aqueous medium without an adjuvant having penetrating properties, the lower eflective limit appears to be about .1%'. If an adjuvant is used, e. g. the wetting, dispersing or emulsifying agents to be mentioned, the lower limit appear to be in the neighborhood of .04%. I prefe to use at least .l% concentration, whether or not an adjuvant is employed. If the compound is used in the form of dusts, I prefer to use concentrationsv of .2% or over. Considerably higher concentrations are generally required, if the compounds arle applied in the form of pastes, mists or aeroso s.

It is to be noted at thi point that the effectiveness of the compounds of'the invention appears to be due in large measure to the fact that they have the property of being able to penetrate into the conducting tissue of the plant, being carried deep into the roots-killing the plant throughout. It is well known that in order for a'herbicide to 4 be fully effective, the herbicide must kill the roots as well as the top or the plant.

The compounds of the invention, therefore, appear to fit the definition of translocated. or "systemic" herbicides. For they do not merely injure the weed at the point of contact; they take the normal path from leaves to roots within the plant and destroy it from within.

Most of the compounds of the invention are practically insoluble in water as far as usual standards oi solubility are concerned. The substituted organic ammonium salts are quite soluble, but many of the other compounds have solubilities of less than 1000 parts per million of water. Those of the others, e. g. the alkali salts.

' which are somewhat soluble in water, tend to' salt out" in hard water. One of the problems solved by the present invention was to find a way for getting the insoluble compounds of the invention into solution or suspension, so as to render it possible to'bring' the necessary concentration to bear on the plant tissue.

The present invention is based in part upon the observation or discovery that wetting. dispersing and emulsifying agents in general will dissolve or suspend from 1 to 50% of their weight of the compounds of the invention and that when such solutions or suspensions are mixed with water in any proportion, a. relatively stable colloidal suspension or solution is formed.

In this connection, it should be noted that generally speaking it is not possible to produce stable solutions of the water-insoluble compounds of the invention by dissolving inorganic solvents those compounds that happen to be soluble in such solvents, and then diluting with water. For the addition of water ordinarily precipitates the compounds.

This invention i not limited in its broad aspects to any particular wetting, dispersing or emulsifying agent. See, for instance A List of Commercially Available Detergents, Wetting, Dispersing sion of Insecticide Investigations of the United States Department of Agriculture published June 1940, and Chapter 11 on Emulsions of Mattiellos Protective and Decorative Coatings, Vol. IV, John Wiley 8: Sons, Inc., New York, 1944. Nor is the invention in its broad aspects limited to agents of either the ionic or non-ionic type, though I do prefer to use those oi the non-ionic type.

Agents of the non-ionic type are those that are not aflected by salts, acids, or bases, whereas those of the ionic type are aflected to the extent that precipitation may occur when a salt, acid or base is added to a solution or suspension of a compound in an ionic agent.

Sulphonated vegetable oils. (e. g. sulphonated castor 011, corn oil, peanut oil, soy bean oil, etc.) are examples of ionic agents that I may use. These have the advantage of cheapness, but bein ionic, they have their limitations when used in the presence of acids. bases and salts. When such agents are used, it is advisable to use distilled or soft water for dilution purposes.

As previously stated, agents of the non-ionic type are preferred; This type of agent will usually dissolve or suspend from 1 to 50% of its volume or weight or the compounds of the invention, and may then be diluted with water to the desired concentration for application to the plant. The usual amounts of salts. acids, or alkalis apparently or suspension.

particularly suitable for the purposes of this invention may be defined as follows:

A water-soluble, non-ionic emulsifying agent containing polyether groups of the formula R.O.(CzH4O)n.R1, where R is an alkyl, aryl, aral-.

kyl, alkyl-aryl or acyl group of 10 carbon atoms or more, and R1 is an alkyl, aryl, aralkyl, alkylll aryl, or acyl group or a hydrogen atom, and n is and Emulsifying Agents by H. L. Cupples, Divi-.

have little, it any, eflect on the resulting solution an integer greater than 2 and generally greater than 10.

Two commercial products answering to the foregoing description, which have been used in practicing the invention, are Tween #20 made by Atlas Powder Company, Wilmington, Delaware,

and Triton NE made by Rohm and Haas Co.,

Philadelphia, Pennsylvania. Tween is apolyoxyalkylene derivative of so'rbitan monolaurate, and Triton NE is a, polyalkylene ether alcohol.

Similarly useful are the polyethylene glycols of molecular weight of 1500 or more, obtainable on the market under the trade-mark Carbowax.

The following are several illustrative examples of herbicidal compositions made according to the teachings of the present invention:

l-naphthoxyacetic acid is used instead of the phenoxyacetic acid of Example 1.

Z-naphthoxyacetic acid is used in Example III instead of the 1-naphthoxy-alpha-propionic acid.

Example V Phenoxyacetic acid is used in Example III instead of the 1-naphthoxy-alpha-propionic acid.

Example I Parts Phenoxyacetic acid Tween #20 or Triton NE 25 Water 9'70 Example II Example VI Parts Z-naphthoxyacetic acid 2 Triton NE 20 Citric acid Water 968 Example VII Parts Potassium Z-naphthoxyacetate 4 Sodium lauryl sulphate 1 Water 995 Example VIII Phenylmercapto-acetic acid is used instead of I the phenoxyacetic acid of Example I.

Example IX Phenylimino-acetic acid is used instead of the phenoxyacetic acid of Example I.

Example X 1-naphthylmercapto-acetic acid is used instead of the phenoxyacetic acid of Example I.

Example XI 2-naphthylimino-acetic acid is used instead of the phenoxyacetic acid of Example I.

Example XII The methyl or ethyl esters of any of the oxy, mercapto or imino monocarboxylic acids are used instead of the naphthoxy propionic acid of Example III.

Example XIII Parts 2.4;5-tri-chlorophenoxyaceticacid 2 Sulphonated castor oil 20 5 Water 973 Example XIV Parts Penta-chlorophenoxyacetic acid 1 Wetting agent such as sulphonated alkyl 10 phenol 10 Water 989 Example XV Parts 2.4.6-tri-bromo-phenoxyacetic acid 2 Sulphonated peanut oil Water 978 Example XVI Parts J 2.3.4.6-tetra-chloro-phenoxyacetic acid 1 Triton NE 10 Water 989 I Example XVII Parts 5 Sodium' p-chlorophenoxyacetate 5 Sulphonated castor oil 40 Water 955 Example XVIII Parts Ethyl 2.4-dichloro-phenoxyacetate 2 Sulphonated alkyl phenol 20 Water 978 Example XIX Parts 2.4-dichloro-phenoxyacetic acid 2 Tween #20 20 Citric acid 10 Water 968 40 Example XX Parts 2.4 dichloro phenoxy alpha propionic acid Triton NE or Carbowax 1500 20 Water 9'78 In each of the foregoing examples, the active ingredient is first dissolved in the wetting, dispersing or emulsifying agent to make up a stock solution. The water may be added at any time before the composition is. to be used.

It is noted that in certain of the examples, citric acid was added. The purpose is to lower the pH, as it has been found that plants take up such chemicals much more readily at a pH of 4 as or less. Any acid may be used, but solid acids as tartaric, succinic, citric, malic, maleic, sulfamic and fumaric are generally more convenient to use for this purpose than the liquid acids. The acid may be added at any time before using the m composition, but it preferably forms part of the stock solution.

In the case of the water-soluble compounds such as the alkali salts and the substituted organic ammonium salts, an aqueous solution of 05 the desired concentration may be made up directly. A wetting agent or a surface tension depressing agent may be added to facilitate penetration. Such agents also appearto step up the herbicidal effect, thereby rendering it possible to use smaller concentrations.

Example XXI Parts Substituted organic ammonium salt 1 to 2 Water 993 to 998 l to 5 Wetting agent The compounds of the invention may also be incorporated into dry compositions containing other active or inactive ingredients. For instance, a suitable dry composition may contain any one or more of the compounds of the invention, a wetting agent in dry form such as Alkanol (sodium tetrahydronaphthalenesulphonate or sodium alkylnaphthalenesulphonate) and an acidii'ying agent, such as citric, tartaric, succinic, malic, maleic, fumaric and sulfamlc acid. The purpose of the acid is to reduce the pH to 4 or less, at which pH the herbicidal compositions are more readily absorbed by the plant. An acid, either solid or liquid, may also be added to the wet com positions. It is advantageous in many cases to add a buffer salt (a salt of any weak acid or base), particularly if the composition contains sulfamic acid.

The following are a few examples of dry compositions suitable for killing weeds: to Example XXII Parts Any of the free acids of the invention 1 Aerosol (American Cyanamid 8: Chemical Corp., New York), or Santomerse (Mom santo Chemical C0,, St. Louis, Missouri)... 1

Talc 98 Example XXIII Parts Any ester of the invention 2 Oil (light motor grade) 3 Talc s 95 The ingredients in each of the foregoing examples are thoroughly ground together in a pebble mill. The resulting compositions are intended to be applied to the leaves of the weeds in the form 01 dusts.

The following are examples of dry compositions which may be mixed with water, and applied to the weeds by spraying:

Example XXIV Parts A water soluble salt or ester of any of the acids previously mentioned.- 2 Filler such as sugar or talc 1 Dry wetting agent such as Carbowax 4000---- 1 The ingredients are mixed and ground to a powder. The powdered mixture may be sold for use as such. The userrneed onl mix one part of the dry powder with 250 to 500 parts of water to form a solution suitable for spraying.

Example XXV Parts Any of the free acids of the invention l Alkali carbonate. e. g. sodium carbonate 1 Non-ionic or alkali-stable wetting agent such as Carbowax 4000 1 Talc or other filler 1 The ingredients are mixed and ground to a powder, which may be sold as such. To prepare for use, the powder is mixed with 125 to 250 times as much water. The alkali carbonate reacts with the acid to form a water soluble salt.

The compositions of the invention lend themselves particularly to application to weeds in the form of fine mists or aerosols. If they are to be applied in this manner, they should be dissolved in a very volatile solvent such as fluorinated hydrocarbon such as tetrafluormethane, halogenated hydrocarbons containing both chlorine and fluorine such as dichlorodifluoromethane (Freon), or dimethyl ether.

The following are a few examples or compounds suitable for application in the form of mists or aerosols:

The compositions made in accordance with the invention may be applied for their intended purpose inseveral diiierent ways.

The most advantageous and presently preferred way is to spray the composition on the leaves or the plant to be exterminated. This method takes advantage of the normal path taken by naturally-occurring hormones.

Another method is to cut of! the top of the stem of the plant, and then bend the stem over into a solution of the herbicide. The plant absorbs suiflcient herbicide in this manner to kill itself.

I am not precluded from using the herbicides of the invention in other 'ways, as by applying them to the roots.

At this point, it is to be noted that the effectiveness of a herbicide can be considerably increased by applying it on a sunny day when the temperature is over 70 F.

It is also to be noted that the compositions of the invention have an accumulative effect on plants, so that by spraying a plant with a composition oi halt strength on two occasion, two or three weeks apart, the plant will be killed, though the first application ltseli. is not sufilcient. i

The compositions of this invention are much more eflective than previously-used chemicals,

and are capable of killing weeds, which are noxious, insidious and persistent like poison ivy in a I period of two to three weeks. They can be applied to large areas at relatively small expense and have the added advantage that unlike prior herbicides they do not render the area sterile. Furthermore, they are not harmful to either man or beast, and can be readily handled without any danger.

In conclusion, it is to be understood that the examples have been given for illustrative purposes only, and that the invention is not to be limited thereto.

This application is a continuation-in-part of my prior application Serial No. 527,357 filed March 20, 1944.

I claim:

1. A method for killing weeds in an active state of growth, which consists in applying to the weeds a substance selected from the group consisting of phenoxy, phenylmercapto, phenylimino, naphthoxy, naphthylmercapto, and naphthylimino monocaroxylic aliphatic acids, their salts and esters, in a concentration of at least about .1% by weight.

2. A method for killing weeds in an active state of growth, which consists in applying to the leaves of the weeds a substance selected from the group consisting of phenoxy, phenylmercapto, phenylimino, naphthoxy, naphthylmercapto, and naphthylimino monocarboxylic aliphatic acids,

their salts and esters, in a concentration of at state of growth,,which consists in applying to the leaves of the weeds an aqueous solution of a substance selected from the group consisting of phenoxy, phenylmercapto, phenylimino, naphthOXY, naphthylmercapto, and naphthylimino monocarboxylic aliphatic acids, their salts and esters, in a concentration of at least about .1% by weight. I

4. A method for killing weeds in an active state of growth, which consists in applying to the leaves of the weeds a composition containing an active ingredient, water and a wetting, dispersing and emulsifying agent, said active ingredient being selected from the group consisting of phenoxy, phenylmercapto, phenylimino, naphthoxy, naphthylmercapto, and naphthylimino monocarboxylic acids, their salts and esters,

in a concentration of at least .04% by weight.

5. A method for killing weeds in an active state of growth, which consists in applying to the leaves of the weeds a composition containing an active ingredient, water and a water-soluble, non-ionic wetting, dispersing and emulsifying agent, said active ingredient being selected from the group consisting of phenoxy', phenylmercapto, phenylimino, naphthoxy, naphthylmercapto, and naphthylimino monocarboxylic aliphaticacids, their salts and esters, and comprising at least about .04% of said composition.

6. A method for killing weeds inan active state of growth, which consists in applying to the leaves of the weeds a composition containing a substance selected from the group consisting of phenoxy,

phenylmercapto, phenylimino, naphthoxy, naphthylmercapto, and naphthylimino monocarboxylic aliphatic acids, their salts and esters, and comprising at least about 114% of the weight of thecomposition, water and a water-soluble, non-ionic emulsifying agent containing polyether groups of the formula R.O.(C2H40)n.R1, where R is an alkyl, aryl, aralkyl, alkyl-aryl, or acyl group of at least 10 carbon atoms, and R1 is an alkyl, aryl, aralkyl, alkyl-aryl or acyl group or a hydrogen atom, and n is an integer greater than 2.

7. A method for killing weeds in an active state of growth, which consists in applying to the leaves of the weeds a'composition containing phenoxyacetic acid, and a wetting, dispersing and emulsifying agent, the phenoxyacetic acid comprising at least about .04% of the composition.

8. A method for killing weeds in an active state of growth, which consists in applying to the leaves of the Weeds a composition containing phenoxyacetic acid, and a wetting, dispersing and emulsifying agent, the phenoxyacetic acid comprising at least about .04% of the composition.

9. A method for killing weeds in an active state of growth, which consists in applying to the leaves of the weeds a composition containing naphthoxyacetic acid, and a wetting, dispersing and emulsifying agent, the naphthoxyacetic acid comprising at least about 114% of the composition.

10. A method for killing weeds in an active state of growth, which consists in applying to the leaves of the weeds a composition containing naphthoxyacetic acid, water and a water-soluble,

leaves or the weeds a composition containing phenylmercapto-acetic acid, and a wetting, dispersing and emulsifying agent, the phenylmercanto-acetic acid comprising at least about .0470

of the composition.

12. A method for killing weeds in an active state of growth, which consists in applying to the leaves of the weeds a composition containing phenylmercapto-acetic acid, water and a water- 'soluble non-ionic wetting, dispersing and emulsifying agent, the phenylmercapto-acetic acid comprising at least about .04% of the composition.

13. A composition for killing weeds in an active state of growth, said composition containing an active ingredient, water and a wetting, dispersing and emulsifying agent, the active ingredient being selected from the group consisting of phenoxy,- phenylmercapto, phenylimino, naphthoxy, naphthylmercapto, and naphthylimino monocarboxylic aliphatic acids, their salts and esters and comprising at least about 114% by weight of said composition. I

14. A composition for killing weeds in an active state of growth, said composition containing an active ingredient, water and a water-soluble, non-ionic wetting, dispersing and emulsifying agent, the active ingredient being selected from the group consisting of phenoxy, phenylmercapto, phenylimino, naphthoxy, naphthylmercapto, and naphthylimino monocarboxylic aliphatic acids, their salts and esters and comprising at least about 114% by weight of said composition.

15. A composition for killing weeds in an active state of growth, said composition containing a substance selected from the group consisting of phenoxy, phenylmercapto, phenylimino, naphthoxy, monocarboxylic aliphatic acids, their salts and esters, and comprising at least about .04% of the weight of the composition, water and a watersoluble, non-ionic emulsifying agent containing polyether groups of the formula RD. (C2H4O)1;.R1,

I where R is an alkyl, aryl, aralkyl, alkyl-aryl, or

non-ionic wetting, dispersing and emulsifying acyl group of at least 10 carbon atoms and R1 is an alkyl, aryl, aralkyl, alkyl-aryl or acyl group or a hydrogen atom, and n is an integer greater than 2. 16. A composition for killing weeds in an active state of growth, said composition containing an active ingredient, water and a wetting, dispersing and emulsifying agent, the active ingredient being phenoxyacetic acid and comprising at least about .04% by weight of said composition.

-17. A composition for killing weeds in an active state of growth, said composition containing an active ingredient, water and a wetting, dispersing and emulsifying agent, the active ingredient being naphthoxyacetic acid and comprising at least about 114% by weight of said composition.

18. A composition for killing Weeds in an active state of growth, said composition containing an active ingredient, water and a wetting, dispersing and emulsifying agent, the active ingredient being phenylmercapto-acetic acid and comprising at least about .04% by weight of said composition.

19. A composition containing a substance selected from the group consisting of phenoxy, phenylmercapto, phenylimino, naphthoxy, naphthylmercapto, and naphthylimino monocarboxylic acids, their salts and esters, mixed with a wetting, dispersing and emulsifying agent, and comprising at least one per cent of the composition, said composition being capable of being mixed with water to form a solution containing ing herbicidal properties.

naphthylmercapto, and naphthylimino containing at ie'asthomty weightfoifsaid naphthoxyacetic acid and havingherbicidal properties.

22. A composition containing phenylmercaptoacetic acid mixed with a wetting, dispersing and emulsifying agent and comprising at least one per cent of the composition, said composition being capable of being mixed with water to form a solution containing at least .04% by weight of said phenyimercapto-acetic acid and having herbicidal properties. 1 g

FRANKIE-DI D. JON E8. 

